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Digital fluid pressure flow rate and position control system

  • US 4,550,747 A
  • Filed: 10/05/1983
  • Issued: 11/05/1985
  • Est. Priority Date: 10/05/1983
  • Status: Expired due to Fees
First Claim
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1. In a fluid pressure control system including a flow control pressure amplification valve having a first port, a second port, a moveable closure element interposed therebetween operated by fluid at a control pressure and in communication with said first port, the improvement comprising a relief line, a control pressure enhancement valve in flow communication with said first port and with said pressure amplification valve, a control pressure reduction valve in fluid communication with said control pressure enhancement valve, said pressure amplification valve and said relief line, a control pressure enhancement solenoid coupled to operate said control pressure enhancement valve, a control pressure reduction solenoid coupled to operate said control pressure reduction valve, a command signal source for providing a digital command control pressure signal corresponding to a desired flow rate between said first and second ports, a control pressure feedback transducer coupled in line between said control pressure enhancement and reduction valves to provide a feedback signal indicative of actual pressure at said control pressure enhancement and control pressure reduction valves of a magnitude amplified by said pressure amplification valve to a factor greater than one for enhanced sensitivity, and electronic digital control means which receives said command control pressure signal and said feedback signal and responsively selects one of said solenoids to provide thereto an error correction signal of duration controlled in accordance with the magnitude of initial difference between said command control pressure signal and said feedback signal and a predicted time at which said difference will approach zero, as determined by iterative resampling of said difference and comparison thereof with a predetermined portion of said initial difference.

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